Thermostat



Aug. 9 1927. 1,638,085

f J. O. CARREY THERMOSTAT Filed May 1, 1925 2 Sheets-Sheet l,

24 r 4 ,ff/6%.

Aug. 9, 1927.v 1,638,085

, J. c. CARREY THERMOSTAT Filed May 1, 1925 2 Sheets-sheet 2 Patented Aug. 9, 1927.

I JOHN 0. CARREY, F ST. LOUIS, MISSOURI,

ASSIGNOR T0 CARREY-MORSE ENGINEER- ING COMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION OF MISSOURI.

riinaimos'riir.

Application led May 1,

y This invention relates to new and useful improvements in thermostats, the primary object being to provide a tliermostatic device for positively operating an electric switch in a predetermined relation with the temperature.

Further objects of the invention are to provide a thermostat which is of strong and durable construction, is sensitive in operation, and is sutliciently powerful to successfully operate the device with which it is associated.

Other objects of the invention are to provide simple means for regulating said thermostatic device to render it operative at certain temperatures. The invention briefly -consists of two thermostatic elements of dissimilar materials havin unequal coefficients of expansion and suitable switch mechanism operable by one of said elements. Oney of` the elements forms a support or casing in which is arrangedthe other one of said elements, the latter having opposed operating or pivot points which engage and operate a lever associated with the switch mechanism. The support element has greater coefficient of expansion and consequently causes the points of the other elements to move to and from each other in accordance with the temperature which causes the expansion and contraction of said support element. Thel switch mechanism preferably includes snap action means for insuring quick -make and break contact.

With thesel and other objectsin view, my invention consists in certain novel features of construction and arrangement of parts, hereinafter more fully described and claimed, and illustrated in the accompanying drawings, in which'- Figure 1 is atop plan view of the device with the cover removed.

i 4 Figure 2 is a vertical cross section taken through the device.

' Figure 3 is a fragmental plan view of' the deviceshowing the same in moved position.

Figurelis a detail view taken on line 4-4 of Figure 1. v

Figure 5 is a top plan view of a. modified form of my improved thermostat with the cover thereof removed.

Figure 6 is a vertical cross section taken longitudinally through the device.

i935. serial No. amai.

Figure 7 is al top plan view of the mechapism and showingthe same in moved posiion. `Referring by numerals to the accompanying drawings, 10 indicates a circular casing, preferably made ofv metal, such as zinc, which has a comparatively high coeilicient of expansion. This casin com rises-a' bottom Wall 11 and anv annulr wa l 12 formed integralwith said bottom wall and provided with an enlarged annulu's lftwhich is internally threaded and 'forms an annular 'shoulder 15. A cover 16 made of the saine metal as the casing'is provided with a circular rib 17 externally threaded for engagement with the threaded portion 14. Alresilient split ring 18, preferably l`formed of steel or other material having comparativelly low coefficient ofexpansionis placed in casing 10 in a close fit with annular wall 12. The ends 1.9 of this ring are preferably tapered to form knife-edgepoints 20 which' are offset relative to each tlier inl radial direction. The coeficient of expansion of ring 18 is considerably less than that of the casing 10 andconsequently when the latter contracts, due to the change in temperature, the annular wall 12 of said casing encircling ring 18 will cause` the latter to contract, bringing the points20 thereof toward each other. Conversely, when casing 10 .expands the annular wall 12 expands outwardly and the resiliency of ring 18 will cause the latter to" expand, thereby moving points 20 away p from each other. This relative movement ofpom'ts 20 is taken advantage of to operate suitable switch mechanism by means of a lever 21, one end 22 of which is provided with oppositely disposed seats 24, preferably gshaped for receiving the knife-edge p oints Connected to lever 21 as indicated at 25 is one end of an arm or link26, the opposite end of which is formed with aslot 27 for engaging an upstanding pin 28. This in v proyects upwardlyv from an. 'arm 2,9 o? a member 30 which is loosely .mounted forA pivotal movement on the lower end of a pin 31,'which'is fixed to the bottom Wall 11 of casing 10.l Pivotally mounted on the upper end of pin 31 is one end of an arm 32, the opposite end of which car-ries a contact blade 31h-.which is adapted to engage either one ico 5 wardly presente l spective side of arm 30. The

of oppositely dis osed contact members 35 and 36, respectivel) fixed to the bottom wall of casing 10.

Member 30 is rovicled .with a pair of upd) lugs 30 arranged on each side of arm 32 and spaced therefrom. An adjusting screw 37 is screw-seated in the threaded aperture of each lug and has its end presented inwardlyfor enga ing the reistanc(` between the operating points of serews` is greater than the width of arm 32, thereby providing lost motion 'for member 30 relative to arm 32. This distance can be regul lated by adjusting screws 37 in order to effeet operation of arm 32 at the desired moment.

A coiled spring 38 is connected at one end to a pin 39 which is carried by arm 32 and 2 is located on the center line thereof and the opposite end of said spring is connected to a pin 40 which is seated in the bottom wall of casing and is arranged in line .with pin 39 and the pivotal axis of arm 32 when the latter occupies -central or neutral position with respect to contacts and 36. In this manner, ,spring 38 constitutes a snap action means for quickly bringing arm 32 to any one of its eXtreme positions as soon as said arm passes its center.

Arm 21 is operated in the direction indicated in Figure 1, which is the cold position, by the contraction of circular wall 12 which 'causes the split ring18 to ymove in- 35 wardly, thereby bringing the oints 20 thereof toward each otherl and roc ing lever 21 in v the direction indicated by the arrow in Fi ure 1. When the circular wall 12 expan s, due to the rise in the temperature, ring 18 4 expandsaccordingly, causing the ends thereof to move'away from each other, whereupon lever 21 is moved in the opposite direction to a position shown in Figure 3. This move-v ment is effected by means of a coiled spring 41 one end of which is connected to lever 21 andthe opposite end of which is anchored to a pin 42 which is fixed to and projects from the bottom 'wall 11 of casing 10. Link 26 is pivotally connected to lever 21 but this pivotal connection is rendered rigid by means of adjusting screws 45 which are screw-seated in lugs 46 laterally pro'ecting from link 26 adjacent to lever 21. crews 45 can be adjusted' to var the relative positions of lever 21 and lin 26 in order that lever 21 can be operated at predetermined temperal tures as indicated by a chartl 47 which isV xed to the bottom wall 11 ,and with which cooperates a rpointer 48 projecting from ever 21. l

A flexible electrical connection 48 is connected to contact blade 34 and contact members 35 and 36 have connected thereto electrical connections 49 and 50, respectively.

' These connections are connected to the elecseated in the e arged threaded trical circuits or ap aratus which it is desired to control or w ich are used to operate suitable mechanism.

In the operation of my device, assuming that the thermostat is used in conjunction with a solenoid switch, such as disclosed in m copending application Serial Number 27,903, filed May 4, 1925, for controlling a refrigerating apparatus, connection 50 is connected to that terminal of the switch which sets the electric motor in operation and connection 49 is connected vto that terminal which disconnects the motor circuit. With the arm 32 in the position shown in Figure 1, which is the cold position, the motor circuit of the refrigerating apparatus is disabled through the interengagement of contact blade 34 with contact 35, thereby rei.- dering the refrigerating apparatus inoperative. This condition will continue until the tem erature of the apparatus rises above a pre etermined degree, whereupon the expansion of casing 10 will release the points 20 of ring 18 sufliciently to allow lever 21 to move tothe position shown in Figure 3 in which position contact blade 34 engages contact 36 which establishes the motor circuit and sets in operation the refrigeratin apparatus driven thereby. The position o arm 32 will remain unchanged, until 'the operation of the refrigeratin apparatus brings the temperature t ereof ow enough to cause contractionof element 10 and the subsequent operation of lever 21 by points 20 of ring 18.

The interrelation of elements 10 and 18 are such that lever 21 is not operated immediately the change in tem erature occurs, b ut a certain range, say of- Eve degrees, is provided before the operation of lever 21 takes place. When lever 21 is o rated, member 30 is rocked on its pivot, t ereby bringing the corresponding screw 37 against arm 32 causing .the latter' to move in the appropriate direction. As soon as arm 32 passes the center line as indicated by -z in Fi re 1, spring 38 imparts snap action to said arm causing it to 'quickly complete its movement,

screws 37 being used only to operate arm 32 durin the first half of its movement.

In t e form shown in Figures 5 to 7, inclusive a. box-shape casing 51 is used and one side thereof is provided with longitudinally disposed bores 52 which receive a air of rods 54 having pointed ends 55 w ich are oiset relativeto the axes thereof. The opposite or outer ends of rods 54 bear against screw lugs 56 which are screwportions 57 of bores 52. Casing 51 is formed of material hav' a hi h coetiicient of expansion, such as zinc, w ile rods 54 are formed of material having a -comparativel low coeicient of expansion so that uring engage either one of stationary contact members 67 and 68. 'A spring 69 connected 'at one endl to arm 64 and anchored at the opposite end to the casing is used to impart snap action to said arir'i; vLever 58 is operated in one direction by therearward movement of points caused by the contraction of casing 5l and said lever is operated: in the opposite direction by a tension spring connected at one end to said lever and at the opposite end to a pin 7 1l which is fixed to the casing.

The operation of 'this device is similar to the device previously described and shown in Figures l to 4. o

The screws 56 force rods lflinwardly dur'- ing the contraction of casing 51 and spring 69 causes said rods to move outwardly when the pressure against said rods is removed by expansion of casing 51.

The wearing surfaces of the thermostatic elements are lubricated by suitable lubricant, preferably by one which is not affected by eXtreme temperatures.

A thermostat constructed according to my invention is simple and positive in operation and is of durable construction as the thermdstatic elements can be -made sufficiently strong to furnish the necessary power for operating the switch or other mechanism.

lVhile I have shown and described a .preferred form of my invention, it is obvious that changes in the construction and arrangement of parts of my'device ycan be*l made without departing from the spirit of my invention.

I claim:

l. A thermostatic device comprising in combination, a circular housing provided with an annular wall, a'resilient split ring arranged' within said housing and bearing against the inner face of said wall, the ends of said ring being offset in radial direction relative to each other, said housing and said ring having different coefiicients of contraction and expansion whereby the contraction pf said housing causes the ends of said ring to move toward each other, a lever arranged in said housing and having one end in fulerum relation with said ends, beingl operable by said ends in' one direction bythe contraction of said housing, a tension member for moving the ,lever in the opposite direction, ay stationary *contact member, a

This arm is pivotally 2. A thermostatic device comprisin in combination, a circular housing provided with `an `annular wall, a resilient split ring arranged within said housing and bearing against the inner face of said wall, the ends of' said ring being oiset in .radial direction relative to each other, said-housing and said ring having different coeiticientso eX- pansion and contraction whereby the con- Itraction of said housing causes the ends of said ring to move inwardly toward each other, a lever arranged in said housing and having one end in fulerum relation with said ends, being operable in one. direction by said -ring by thel contraction of said. housing, a tension member for moving the lever in the opposite direction, a stationary contact mem-- ber, a switch blade pivotally vmounted in said housing and movable into engagement with said contact member, an element pivotally connected at one end to sa'id lever, means carried by said element and engaging said lever at points disposed on each side of said pivotal connection f said element and said lever, said means being adjustable to vary the posi-tion of the lever and render it operable at different temperatures, a member having lost motion connection with said ieu switch blade and operable by the opposite end of said element, and a spring .for im parting snap action to said switch blade- 3. A thermostat'ic' device comprising in combination, a housing of metal havin a high coefficient of expansion, said housing being provided with an integral circular. wall, a resilient split ring arranged within said housing and bearing against the inner face of said wall, said ring having a. vcomparatively low coeilicientv of expansion whereby the ends of-said ring are .caused to 'u'p-fj''- move relative to each other in accordance with the expansion and contraction of said housing, a lever arranged in said hous' and in operative engagement with the ends' I of said ring, the latter being offset relative to each other to form cooperating oppositely A disposed fulcrums for said lever, a coiled spring having one end fixed and the opposite end connected to said lever for movin said lever inone direction, said4 split ringgb adapted to move said lever in opposite direceing tion, a stationary contact member, a, switchl blade pivotally mounted in said housing and j movable into and out of engagement with said conta-ct -melnber, a. plate pivotally' mounted in said housngcoaxially with said switch blade members carried by said plate and disposed oneach -side of said switch blade and adapted to engage the latter when said plate is actuated, an element. xedly connected to said lever at one end and having a pin andslot connection with said plate for, actuating through said members said blade, and a coiled spring connected to said switch blade and t'o a fixed point for imparting snap action thereto;v

4. A thermostatic device comprising in combination, a housing of metal having a high coefficient of expansion, said housing being provided with an integral circular wall, a resilient split ling arranged within said housing and bea-ring against the-inner face of'said wall, said ring having a comparatively low coeicient /f expansion whereby the ends of said ring are caused to move relative to each other in accordance' with the ex ansion and contraction of said housing, a ever arranged 1n said housing and in operative engagement with the ends of said ring, the latter being'ofset relative to eachother to form cooperating oppositely disposed fulcrums #er actuating said lever in'one direction, a coiled spring for moving `saidlever in opposite direction, a link pivotally connected at one end to saidlever and provided with lateralears spaced from said lever and arranged to each side of 'the pivotal yconnection of said lever and said link` a screw adjustably seated in each lu and bearing against said lever, said screws eing adjustableto vary the relative positions of said link and said lever with respect to each v other and rendersaid lever operable at differentv temperatures,- and a switch mechinilm'operated by the opposite end of said 5. A -thermostatic device comprising in combination a housing of metal having a high coefficient of expansion, 's'aid housing .being provided with an integral circular wall, a resilient split ring arranged within said .housing and bearingagainstthe inner face of said wall, said riii'gf'thaving a comaratively low coeicentoffexpansion wherey the ends of said ring are caused to move relative toeach other in accordance with the expansion and contraction of said housing, a lever looselyy arranged in said housing and in operative engagement with the ends of said ring, the latter being offset relative to each other to form cooperating oppositely disposed fulcrums for said lever, a contact arm pivotally mounted in said housing, a link connected to said lever and extending at an angle therefrom, means for fixedly adjusting the positiony of said lever with respect to said link, thereby rendering the latter responsive to different temperatures, and a member operatively connected to said link and having lost motion operative connection with said contact arm. l

6.1A therinostatic device comprising in combination, a housing of metal having a high coefiicient of expansion, said housing being provided with an integral circular wall, a resilient split ring arranged within said housing and bearing against the inner face of said wall, said ring having a com-.

paratively low coeflicient of expansion wherebythe ends of said ring are caused to move relative to each other in accordance with the expansion and contraction of said housing, a lever loosely arranged lin said housing and in loperative engagement "with the ends of said ring, the latter being offset relative to each other to form cooperating oppositely disposed fulcrurns for actuating said lever,y

stationary contajct member, a contact arm pivotally mounted in said housing and movable into and out of engagement with said lstationary contact member, a link connected at one end to ,said lever, means for interengaging said lever and said link to adjust said lever and render it operable at different teniperatures, a stationary mark indicia -member cooperating with the free end of said leverto indicate the Vextent of adjustment thereof, amember operatively connected to the opposite end of said link and having lost motion operati-ve connectionv with said/contact I arm, anda tension member connected to said contact arm for importing snap action" thereto, l i

In testimony whereof I hereunto ailix my signaturethis' 22nd day of April, 1925.

`JOHN vO. CARREY.' 

